JP2010159757A - Method and apparatus to facilitate cooling of diffusion tip within gas turbine engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus to facilitate cooling of a diffusion tip used for a fuel nozzle. <P>SOLUTION: The diffusion tip 306 has a substantially circular body including an outer surface 401 and an opposite inner surface 403. The diffusion tip body 306 extends from a discharge end 407 to an inlet end 405. The diffusion tip 306 includes an inlet surface 402 adjacent to the discharge end and defined within the body. A discharge surface 400 is defined opposite the inlet surface. A plurality of diffusion apertures 404 each extend between the discharge surface 400 and the inlet surface 402, each aperture 404 is oriented relative to the body 306 to discharge a diffusion flow outward therefrom at an angle γ (gamma) measured in an X-Z plane between a center line of the diffusion aperture 404 and an X-axis extending tangentially to the outer surface, and at an angle θ(theta) measured in a Y-Z plane between the center line of the aperture and a Y-axis extending radially outward from the center line. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates generally to gas turbine engines, and more particularly to a fuel nozzle diffusion tip for use in a gas turbine engine.

  In at least some known gas turbine engines, igniting the fuel mixture in the combustor produces a flow of combustion gas that flows downstream through the hot gas flow path to the turbine. Compressed air flows from the compressor to the combustor. Known combustor assemblies are provided with a fuel nozzle to facilitate the introduction of fuel and air into a combustion zone defined within the combustor. In the turbine, the thermal energy of the combustion gas stream is converted into mechanical energy that rotates the turbine shaft. Power can be supplied to a machine such as a generator or a pump by the output of the turbine.

  At least some known fuel nozzles are provided with diffusion tips. The diffusion tip is a passage through which fuel, air, or a combination of both pass and which functions with the main premixing circuit of the fuel nozzle. After the fuel and / or air are mixed, they are discharged from the tip, ignited, and transported to the combustion zone.

  During operation, it is common for fuel and / or air to flow through a plurality of passages formed in a known diffusion tip and burn after exiting the diffusion tip. In that case, the outer surface of the diffusion tip is exposed to high-temperature combustion gas. Thermal stress occurs in the diffusion tip that is continuously exposed to high temperatures. Such thermal stress causes cracks and / or mechanical failure in the diffusion tip over time. At least some known diffusion chips are provided with various cooling circuits to promote a temperature drop of the diffusion chip. However, such a cooling circuit is disadvantageous because the fuel concentration is high and soot is likely to adhere to the diffusion chip. If soot adheres, the flow characteristics of the fuel nozzle will be adversely affected and the combustion temperature will rise. Changes in flow characteristics and further increases in combustion temperature adversely affect the operation of the fuel nozzle components. For example, when a metal alloy is thermally deteriorated or annealed, the structural integrity of the component parts deteriorates.

  Also, increasing the operating temperature of the diffusion tip prematurely wears combustor machinery near a flame, such as a combustor liner and / or transition piece assembly. As a result, compared to when the combustion temperature is maintained at a low temperature, the mechanical equipment of such a combustor needs to be frequently replaced, and the repair cost increases. At least some known combustors use special alloy components that are highly resistant to thermal wear to accommodate high temperature operation. However, an engine using a special alloy component having high heat resistance is higher in cost and weight than an engine that does not use such a component in a combustor.

US Pat. No. 7,024,861B2 US Pat. No. 6,698,207B1 US Pat. No. 6,453,673 B1 US Pat. No. 6,460,340 B1 US Patent Application Publication No. 2007 / 0214790A1 US Patent Application Publication No. 2007 / 0119177A1 US Patent Application Publication No. 2007 / 0044477A1 US Patent Application Publication No. 2006/0191268 A1

  Accordingly, there is a need to provide a method and apparatus that facilitates cooling a diffusion tip of a gas turbine engine.

  In one embodiment of the present invention, a method for assembling a gas turbine engine is disclosed. The method includes providing a fuel nozzle having a diffusion tip that includes a body having a substantially circular cross-sectional area. The diffusion tip body has an outer surface, an inner surface opposite the outer surface, and an inlet surface adjacent to the end of the body. The entrance surface is located radially inward from the inner surface of the main body. The diffusion tip body further has a discharge surface opposite the inlet surface. The method further includes coupling the fuel nozzle into the combustor assembly such that each of the plurality of diffusion holes extending from the discharge surface to the inlet surface is oriented to discharge a diffusion flow from the fuel nozzle. The diffusion flow is an angle extending on the XZ plane, forming an angle γ (gamma) between the center line of the hole and the X axis extending tangential to the outer surface, and It is discharged at an angle extending on the Y-Z plane and having an angle θ (theta) measured between the center line and the Y axis extending radially outward from the center line.

  In another embodiment of the present invention, a diffusion tip for use in a fuel nozzle is disclosed. The diffusion tip has a generally circular body that includes an outer surface and an opposite inner surface. The diffusion tip body extends from the discharge end to the inlet end. The diffusion tip includes an inlet surface defined in the body adjacent the discharge end. A discharge surface is defined on the opposite side of the inlet surface. A plurality of diffusion holes respectively extend between the discharge surface and the entrance surface, and each hole extends in a direction tangential to the center line and the outer surface of the hole on the XZ plane with respect to the main body. An angle γ (gamma) is formed between the axis and the angle θ (theta) between the center line of the hole and the Y axis extending radially outward from the center line on the YZ plane. Instead, it is oriented to discharge the diffusion flow outward.

  In yet another embodiment of the present invention, a combustor assembly for use in a gas turbine engine is disclosed. The combustor assembly includes a combustor and a fuel nozzle. The fuel nozzle is configured to discharge fuel into the combustor. The fuel nozzle has a diffusion tip having a generally circular body that extends from the inlet end to the discharge end, and an inlet surface is defined in the body adjacent the discharge end. The main body has a discharge surface opposite to the inlet surface and a plurality of diffusion holes each extending from the discharge surface to the inlet surface. Each hole forms an angle γ (gamma) with respect to the main body on the XZ plane between the center line of the hole and the X axis extending tangentially to the outer surface, and YZ The plane is oriented so as to discharge a diffusion flow at an angle θ (theta) between the center line and the Y axis extending radially outward from the center line on a plane.

1 is a schematic diagram of an example of a gas turbine engine. It is a schematic sectional drawing of an example of the combustor applicable to the gas turbine engine shown in FIG. It is a cross-sectional perspective view of an example of the fuel nozzle assembly applicable to the combustor shown in FIG. It is a cross-sectional perspective view of an example of the diffusion chip applicable to the fuel nozzle shown in FIG. It is a top view of an example of the diffusion chip applicable to the fuel nozzle shown in FIG. It is an expanded sectional view of an example of the diffusion chip shown in FIG. FIG. 5 is an enlarged cross-sectional view of an alternative embodiment of the diffusion chip shown in FIG.

  FIG. 1 is a schematic diagram of an exemplary gas turbine engine 100. Engine 100 includes a compressor assembly 102 and a combustor assembly 104. The engine 100 also includes a turbine 108 and a compressor / turbine common shaft 110 (sometimes referred to as a rotor 110).

  In operation, air passes through the compressor assembly 102 from which compressed air is supplied to the combustor assembly 104. The fuel flows to a combustion zone and / or combustion zone defined within the combustor assembly 104, and the fuel and air are mixed and ignited. The generated combustion gas flows to the turbine 108, and the thermal energy of this gas stream is converted into mechanical rotational energy. The turbine 108 is rotatably connected to the shaft 110. As used herein, the term “fluid” refers to any fluid medium or material including, but not limited to, gas and air.

  FIG. 2 is a schematic cross-sectional view of the combustor assembly 104. Combustor assembly 104 is coupled in fluid communication with turbine assembly 108 and compressor assembly 102. In the illustrated embodiment, the compressor assembly 102 includes a diffuser 112 and a compressor discharge plenum 114 that are coupled in fluid communication with each other.

  In the illustrated embodiment, the combustor assembly 104 has an end cover 220 that structurally supports a plurality of fuel nozzles 222 arranged in an annular fashion about a turbine housing (not shown). The end cover 220 is connected to the combustor casing 224 using a holding fitting (not shown in FIG. 2). A combustor liner 226 defines a combustion chamber 228 and is coupled within the casing 224. A combustion chamber annular cooling passage 229 is defined between the combustor casing 224 and the combustor liner 226.

  A transition section or transition piece 230 is connected to the combustion chamber 228, whereby the combustion gas generated in the combustion chamber 228 flows toward the downstream turbine nozzle 232. In the illustrated embodiment, the transition piece 230 has a plurality of openings 234 in the outer wall 236. The transition piece 230 also has an annular passage 238 between the inner wall 240 and the outer wall 236.

  In operation, the turbine assembly 108 drives the compressor assembly 102 via a shaft 110 (shown in FIG. 1). As the compressor assembly 102 rotates, compressed air is discharged into the diffuser 112 as indicated by the arrows exiting the assembly 102. In the illustrated embodiment, the majority of the air discharged from the compressor assembly 102 flows through the compressor discharge plenum 114 toward the combustor assembly 104 and the remaining portion of the compressed air is directed toward the components of the engine 100. To cool these parts. More specifically, pressurized compressed air in the plenum 114 flows to the transition piece 230 passage 238 through the outer wall opening 234. Air then flows from the annular passage 238 of the transition piece 230 to the combustion chamber cooling passage 229. The air discharged from the passage 229 flows to the fuel nozzle 222.

  In the combustion chamber 228, fuel and air are mixed and ignited. Casing 224 facilitates isolation of combustion chamber 228 from the external environment, such as surrounding turbine components. The generated combustion gas flows from the combustion chamber 228 through the guide groove 242 of the transition piece toward the turbine nozzle 232. In the exemplary embodiment, fuel nozzle assembly 222 is coupled to end cover 220 via fuel nozzle flange 244.

  FIG. 3 is a cross-sectional view of fuel nozzle assembly 222. The fuel nozzle assembly 222 includes an inlet flow conditioner (IFC) 300, a swirl assembly 302 with fuel injection, an annular fuel / fluid mixing passage or premixing circuit 304, and a central diffusion flame fuel nozzle assembly or diffusion tip 306. The fuel nozzle assembly 222 also includes a high pressure plenum 308 having an inlet end 310 and a discharge end 312. The plenum 308 circumscribes the nozzle assembly 222. The discharge end 312 does not need to circumscribe the nozzle assembly 222 and may extend into the combustor reaction zone 314. IFC 300 includes an annular flow passage 316 defined by a cylindrical wall 318. Wall 318 defines an inner diameter 320 of passage 316 and a porous cylindrical outer wall 322 defines an outer diameter 324. A porous end cap 326 is connected to the upstream end of the fuel nozzle assembly 222. In the illustrated embodiment, the channel 316 has at least one annular guide vane 328 on the channel 316. In the illustrated embodiment, the nozzle assembly 222 further defines a premixed gas fuel circuit in which fuel and compressed fluid are mixed prior to combustion.

  FIG. 4 is a perspective view of the diffusion chip 306. FIG. 5 is a plan view of the diffusion chip 306. In the illustrated embodiment, the diffusing tip 306 has an outer surface 400 and an opposite inner surface 402. In the illustrated embodiment, the outer surface 400 is configured as a discharge surface and the inner surface 402 is configured as an inlet surface. The main body of the diffusion tip 306 has a substantially circular cross section, and includes an outer surface 401, an inner surface 403 opposite to the outer surface 401, an inlet end 405, and a discharge end 407. The diffusion tip 306 also has a plurality of diffusion holes 404 for supplying diffusion fuel and / or air to the combustion zone. In the illustrated embodiment, the surface 400 is substantially flat. The shape of surface 400 may alternatively be concave, convex, or as diffusion tip 306 described herein, including fluid flow characteristics and flame retention characteristics with diffusion tip 306 described herein. It can be anything that works.

  In the illustrated embodiment, each of the diffusion holes 404 has a front opening 406 and a rear opening 408 opposite the front opening 406, with each diffusion hole 404 between the front opening 406 and the rear opening 408. It extends to. The front opening 406 is defined along the ejection surface 400 and the rear opening 408 is defined along the inlet surface 402. In the illustrated embodiment, each of the front openings 406 is defined at a radius R of the axial centerline 410 of the diffusing tip 306. Alternatively, the openings 406 may be positioned in any orientation that allows the diffusion tip 306 to operate as described herein. In the illustrated embodiment, the diffusion tip 306 has multiple rows of diffusion holes 404. The diffusion holes 404 may be composed of an arbitrary number of holes 404 arranged in a circle at intervals 505 in the circumferential direction for each row.

In the illustrated embodiment, the front openings 406 are each defined with a diameter D within the radial inner wall 412. The diameter of the cooling or diffusion hole 404 is:
D = d ₀ + d ₁ × ((R ₀ −r) / R ₀ ) ^0.2 × (1 / N) ^0.4
It is represented by Where N is the number of rows of cooling holes, d ₀ and d ₁ are empirical experimental coefficients, R ₀ is the average radius of the cooling holes, and r is the radius of the row. In one embodiment, the diameter D is about 0.030 to about 0.060 inches. Each of the diffusion holes 404 may be oriented at various angles (discussed in detail below), and its cross-sectional shape may be circular, elliptical, or other such that the diffusion tip 306 functions as described herein. Any thing may be sufficient.

  The front openings 406 are arranged such that the X axis of the front opening 406 is aligned substantially tangential to the circle of radius R, the Y axis is aligned substantially perpendicular to the X axis in the radial direction, and the Z axis is the center line 410. Are defined at coordinate positions that are substantially parallel to each other. The angle from the X axis on the XZ plane is γ (gamma), and the angle from the Y axis on the YZ plane is θ (theta). In the illustrated embodiment, each of the diffusion holes 404 is provided along a line F extending from the corresponding front opening 406 at an angle γ and an angle θ. Accordingly, the diffusion holes 404 are arranged in a spiral shape with the diffusion tip 306 as the center.

The angle γ is:
γ = a + b × (( R e, swirler -r) / R e, diffusion) 0.74
It is represented by Here, a and b are empirical experimental coefficients _{, Re, swirler} is the Reynolds number of the swirler assembly 302 _{, and Re , diffusion} is the Reynolds number for cooling the diffusion tip 306. In one embodiment, the angle γ is between about 15 ° and about 60 °.

FIG. 5 shows a diffusion tip 306 and a plurality of circular diffusion hole arrays 500. Each of the diffusion hole arrays 500 is located on a radius that is between the center line 410 and the center 502 of the holes corresponding to the respective array. For example, the first diffusion hole array 500 is located on the radius R1, and the second diffusion hole array 501 is located on the radius R2. The center 502 of each hole is defined at the midpoint of the major axis 504 of the front opening 406. In the illustrated embodiment, the diffusion holes 404 and corresponding arrays 500 and 501 include at least one hole 404 that faces toward the centerline 410. Further, in the illustrated embodiment, innermost array 501 includes an inward diffusion hole 404 that forms an angle β (beta) between radius R 2 and hole major axis 504. The angle β is:
β = c + d × (T _firing / T _cooling ) ^1.16
It is represented by Here, c is an empirical experimental coefficient, d is determined by the above formula for the diameter D, T _firing is the flame temperature, and T _cooling is the cooling air temperature. In the illustrated embodiment, the angle β (beta) is between about 0 ° and about 90 °. Alternatively, the outermost array 500 may have diffusion holes 404 that make an angle β (beta) in the inward direction and / or make an angle α (alpha) between the radius R1 and the axis 504 in the outward direction. . The angle α is determined by the same formula as the angle β described above. In one embodiment, the angle α (alpha) is about 90 ° to about 180 °. In one embodiment, outermost circular array 500 includes a plurality of diffusion holes 404 that are oriented at least partially at an angle α (alpha) and at least partially at an angle β (beta), in alternating orientations. Have.

  In the illustrated embodiment, the angles γ (gamma) and θ (theta) can be variously selected to efficiently cool the ejection surface 400 of the diffusing tip 306. More specifically, the angle γ (gamma) is selected to ensure that small exfoliation bubbles are generated after the diffusion holes 404. A cooling air film layer over the entire discharge surface 400 can be formed by the peeling bubbles. The angle θ (theta) can be variously selected so that a substantially uniform cooling air film layer is distributed over the entire diffusion surface 400. Furthermore, in the exemplary embodiment, a combination of angles γ (gamma) and θ (theta) is selected that can cool the diffusion tip to the maximum. In addition, the radius R1 and / or R2 of the diffusion hole 404 and the circumferential spacing 505 are selected to optimize the thermal gradient and other combustion characteristics of the diffusion tip 306. Also, the hole interval can be selected so as to effectively reduce the stress concentration of the diffusion tip 306.

  An alternative embodiment of the diffusion tip 306 is shown in FIGS. More specifically, the diffusion chip 306 is configured as a convergence chip 600 in FIG. 6 and as a diverging chip 700 in FIG. The converging tip includes a plurality of holes formed with an opening 408 having a larger cross-sectional area than the opening 406. As shown in FIG. 6, since the opening 408 is larger than the opening 406, a convergence path is formed between the opening 408 and the opening 406. In FIG. 7, conversely, since the cross-sectional area of the opening 408 is smaller than that of the opening 406, the diverging hole 700 is defined between the opening 408 and the opening 406. Depending on the orientation of the diffusion holes 404, the thickness of the diffusion tip 306 between the surface 400 and the surface 402, the pressure drop across the diffusion tip 306, and the required heat transfer coefficient of the tip 306, the fuel nozzle 222 A converging diffusion chip 600 or a diverging diffusion chip 700 can be used. In an alternative embodiment, both converging and diverging holes can be used in combination to more effectively cool the diffusion tip.

  During operation, the diffusion tip 306 is effectively cooled by discharging airflow from the diffusion hole 404. The diffusion flow from the hole 404 becomes the flow of the diffusion circuit, is mixed with the flow of the premixing circuit, and co-rotates. As a result, the combustion recirculation zone formed adjacent to the diffusion tip 306 is stabilized. By appropriately selecting the angular direction of the diffusion hole 404, the flow of the premixing circuit and the diffusion flow discharged from the diffusion hole 404 are optimally mixed and / or co-rotated, and the tangential velocity and axial velocity of the discharge flow are obtained. Can be controlled. By co-rotating the flow of the diffusion circuit and the flow of the premixing circuit, it becomes easy to prevent contact between the flame due to combustion and the diffusion tip surface 400, so that overheating of the entire diffusion tip surface can be suppressed and / or carbon black Formation can be reduced. By stratifying the flow of the premixing circuit and the diffusion flow, the cooling film effect is increased, the temperature gradient of the diffusion tip is suppressed, and the soot adhesion can be reduced. By varying the direction of the diffusion hole 404 in various ways, the internal surface area of the diffusion tip 306 increases, so that the diffusion tip can be easily cooled and the residence time of the cooling diffusion flow increases, and the heat transfer coefficient of the diffusion tip 306 increases. Will increase. In addition, during operation, the swirling of the premixing circuit flow and the diffusion flow facilitates swirling of the overall flow. As a result, mixing and / or combustion can be performed effectively in the combustion chamber, and the swirling axis is stabilized, so that the combustion thermoacoustic effect and flame vibration are reduced.

  Some advantages of the present invention over known diffusion tip structures are listed. For example, one of the advantages of the diffusion tip described herein is that tilting the diffusion holes effectively creates a cooling flow over the entire discharge surface of the diffusion tip. Another advantage of the diffusion holes described herein is that the thermal stress applied to the diffusion tips is reduced by making the combustibles such as accumulated soot difficult to contact the fuel and diffusion tips. Yet another advantage of the diffusion holes described herein is to increase the heat transfer efficiency and cooling efficiency of the diffusion tips. A further advantage of the diffusion hole described in the specification is that the diffusion tip can be made of a less expensive material and the manufacturing costs can be reduced by reducing the temperature gradient that occurs in the diffusion tip.

  The embodiment of the method and apparatus for uniformly cooling the diffusion chip used in the gas turbine engine has been described in detail above. Embodiments of the present invention include not only the specific embodiments described herein, but also the configuration in which the components used in the system according to the present invention are used separately from the other components described herein. Embodiments in which the steps of the method according to the invention are performed independently of the other steps described herein are also included in the embodiments of the present invention. For example, embodiments of the fuel supply system and method according to the present invention can be implemented in combination with other fuel supply systems and methods as well as those described herein. Moreover, the form illustrated in the present specification can be applied to various other gas turbine engines.

  Some features of various embodiments according to the present invention may not be shown by the drawings for convenience of explanation. The features shown in one drawing and the features shown in other drawings can be combined in any way, and such embodiments are also intended to be included within the scope of the claims of the present invention.

  The present invention has been described herein using various examples, including the best mode. This allows a person skilled in the art to make any device or system according to the invention or to carry out the method according to the invention. The patentable scope of the invention is set forth in the appended claims, but includes other embodiments that occur to those skilled in the art. As long as such other embodiments have components that do not differ from the words recited in the claims, or have equivalent components that are essentially the same as the words recited in the claims, the present invention Within the scope of the following claims.

  While the invention has been described in terms of various embodiments, it will be apparent to those skilled in the art that modifications may be included within the scope of the claims.

DESCRIPTION OF SYMBOLS 100 Gas turbine engine 102 Compressor assembly 104 Combustor assembly 108 Turbine assembly 110 Compressor / turbine shaft 112 Diffuser 114 Compressor discharge plenum 220 End cover 222 Fuel nozzle assembly 224 Combustor casing 226 Combustor liner 228 Combustion chamber 229 Combustion chamber cooling passage 230 Transition Piece 232 Turbine nozzle 234 Outer wall opening 236 Outer wall 238 Transition passage annular passage 240 Inner wall 242 Transition piece guide groove 244 Fuel nozzle flange 300 Inlet flow conditioner (IFC)
302 Swirler assembly 304 Passage / premix circuit 306 Diffusion tip 308 High pressure plenum 310 Inlet end 312 Discharge end 314 Combustor reaction zone 316 Annular flow passage 318 Cylindrical wall 320 Inner diameter 322 Porous cylindrical outer wall 324 Outer diameter 326 Porous end cap 328 annular guide vane 400 outer surface / diffusion tip surface / discharge surface 401 outer surface 402 opposite inner surface / inlet surface 403 opposite inner surface 404 diffusion hole 405 inlet end 406 front opening 407 discharge end 408 rear opening 410 Axis direction center line 412 Radial inner wall 500 First diffusion hole array / outermost circular array 501 Second diffusion hole array / innermost array 502 Center 504 Hole major axis 505 Circumferential interval 600 Converging tip 700 Diverging hole / diverging tip

Claims (10)

A diffusion tip (306) for use in a fuel nozzle (222),
A generally circular body having an outer surface (401) and an inner surface (403) opposite the outer surface and extending from the discharge end (407) to the inlet end (405);
An inlet surface (402) defined in the body adjacent to the discharge end;
A discharge surface (400) opposite the inlet surface;
A plurality of diffusion holes (404) each extending between the discharge surface and the inlet surface, each being in the center line (502) and the outer surface of the hole on the XZ plane with respect to the main body An angle γ (gamma) is formed between the tangentially extending X-axis and the hole center line and Y extending radially outward from the center line on the Y-Z plane. A diffusion tip comprising a plurality of diffusion holes (404) oriented to discharge the diffusion flow outwardly at an angle θ (theta) with the shaft.   The diffusion tip (306) of claim 1, wherein each of the plurality of diffusion holes (404) is disposed with at least one of a variable radial spacing and a circumferential spacing (505).   The diffusion tip (306) of claim 1, wherein each of the plurality of diffusion holes (404) includes a tapered hole. Each of the plurality of diffusion holes (404) includes at least one of a convergent tapered hole (600) and a divergent tapered hole (700);
The diffusion tip (306) of claim 3, wherein the converging tapered holes and the diverging tapered holes increase internal surface area and increase heat transfer efficiency.   The diffusion tip (306) of claim 1, wherein the ejection surface (400) is substantially concave. The plurality of diffusion holes (404) define a group of inner arrays (501) and a group of outer arrays (500);
The inner array includes at least one diffusion hole located within a first radial extent and inclined at an angle β (beta) with respect to the first radius and the hole major axis;
The outer array includes at least one diffusion hole located within a second radial extent and inclined at an angle α (alpha) with respect to the second radius and the hole major axis;
The diffusion tip (306) of claim 1, wherein the first radial extent is smaller than the second radial extent.   The diffusion tip (306) of claim 6, wherein the outer array further comprises a plurality of diffusion holes (404) inclined at alternating angles α (alpha) and β (beta). A combustor,
A combustor assembly (104) for use in a gas turbine engine (100) having a fuel nozzle (222) having a diffusion tip (306) configured to discharge fuel into the combustor;
The diffusion tip is
A generally circular body having an outer surface (401) and an inner surface (403) opposite the outer surface and extending from the inlet end (405) to the discharge end (407);
An inlet surface (402) defined in the body adjacent to the discharge end;
A discharge surface (400) opposite the inlet surface, and
A plurality of diffusion holes (404) each extending from the discharge surface to between the inlet surfaces, each of the holes relative to the main body on the XZ plane on the center line (502) of the holes And an X-axis extending tangentially to the outer surface and forming an angle γ (gamma) and extending radially outward from the center line and the center line on the YZ plane A plurality of diffusion holes (404) oriented to discharge a diffusion flow at an angle θ (theta) with the Y axis.
Combustor assembly.   The combustor assembly (104) of claim 8, wherein each of the plurality of diffusion holes (404) is disposed with at least one of a variable radial spacing and a circumferential spacing (505).   The combustor assembly (104) of claim 8, wherein the discharge surface (400) is substantially concave.

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